Regulation of actin polarization by Edwardsiella piscicida during invasion of Sebastes schlegeli intestinal mucosa and cellular immune responses.

Intestinal epithelial cells play a crucial role in teleost defence against complex aquatic environments. However, the study of intestinal mucosal immunity in teleosts has been hindered by the lack of reliable and specific marker genes to distinguish between different cell types. In this study, single-cell RNA-seq analysis of the intestinal epithelial cells from healthy and infected Sebastes schlegeli was performed to investigate the heterogeneity of teleost intestinal epithelial cells. Immune cells, including T cells, B cells, non-specific cytotoxic cells (NCCs) and myeloid cells, and non-immune cells including enterocyte, erythrocyte, BEST4+ cell, goblet cell and enteroendocrine cell, were identified. Several notable cell populations, including early myeloid cells, lysosome-rich enterocytes, enterocyte progenitors and BEST4+ cells, were characterized in detail. Additionally, significant changes in the expression of actin polymerization-related genes were observed in various intestinal mucosal cell types following Edwardsiella piscicida infection, suggesting a mechanism of invasion with E. piscicida. These findings enhance our understanding of teleost intestinal cellular composition and provide valuable insights for the development of therapeutic strategies against E. piscicida.